Apparatus for testing audion tubes



1935 P. F. JACKSON I 2,012,045

APPARATUS FOR TESTING AUDION TUBES Filed July 30, 1931 Patented Aug. 20, 1935 1 UNITED;- stares PATENT oFricEif I 7 "2,012,045 nrraaarns Foa TESTING AUDION TUBES Paul F. Jackson, Dayton, Ohio, assignor to The V Radio Products Company, Dayton, Ohio, a cor- Y porationof Ohio Application July so, 1931, serial No. 554,042

.9 Claims. v(c1. 250- 27)v 1 This invention relates to an apparatus for testingaudion tubes, such as arecommonly used in radio receiving sets, and more particularly-to anapparatus. adapted to test tubes of alargenu'm- 5 ber of, difierent types; In tube testing apparatusof thislki'nd the indicating deviceusually consists ofamilliammeter, the scale of which is graduated in amperes or other units to indicatethe quantity of current in a plate circuit... The normal plate 10 current diifers in tubes of. differenttypes and the amount of current whichwould indicate that a tube of, one typewas of high valuemight also indicate that a tube of another type wasof little or no value. Consequently in order to interpret 5 the readingon suchqan apparatus the operator must be, so familiar with thevarious types of tubes undergoing test that he knows the. normal value of the plate current in eachtype of tube, The reading on such an apparatus means nothing to the novice orto a purchaser oftubes who is not. skilled in I such matters. 7

Oneobject of the present invention isyto pro vide an apparatus of this kindwhich' willin'dicate the value ofv the plate current in termsjof tube.

25, quality which will be understandable to any-observer whether skilled or unskilled in this, art.

- A further object of the invention is to provide such; an apparatus in which the same quality in.

any tube testedthereon willbe indicated by the same designationregardless of the type of tube.

Testing apparatus ,of this kind is often provided with a large number of tubesockets whichare; marked with numbers or other indications to 403 particular socket which is to receive. the tube.

To facilitate this op erationjit is a further object of" the invention to provide ineans'controlled by the selecting device to indicate the socket selected. Other objects of. the invention will appear as 45. the apparatus is described in detail.

The accompanyingdrawing is a diagram of the circuits for an apparatus embodying my invention.

In this drawing I have'illustratedone embodi-i mentfof the invention but it will be understood that thisparticular embodiment has been chosen for thepurposes of illustration only and that the apparatus mayltake variousforms without (16-3. parting vfromthespirit 19f: the invention; Ap- 5 paratus of this kind usuallyicontains a large m m her of sockets, frequently twenty-five ormore, and for the purpose of simplifying the illustration I have shown'the present apparatus as having but 'three sockets but it will be obvious that any de- M sired number of sockets may be utilized by adding 5 terminal P. The tube i also includes a screens. 10

These terminals may be supplied with current in. the usual or any suitable manner and, in the present instance the filament terminals F are connected by a conductor 4 with one end of the secondary winding ii'oi a transformer, the primary 15 winding 6 of which is adapted to beconnected with a suitable'source of supply for alternating current and is usually provided with means 7 whereby it may be plugged in an ordinary light socket. The filament terminals F of the several 201 sockets are connected by conductors i with the secondary h atvarious distances from that end of the secondary which is connected with thefilament F, the points of connection being de termined by the characteristics of the tubes which 25 are'to be tested in the respective sockets. Thegrid is connectedby a conductor 8 with'one end of a second secondary windings, the other endof whichis connected with a conductor l 0 which leads to a terminal ll adapted tobe connected with a .30

source of current, or bias supply, of any suitable character, such as a battery. The plates P are 1 liammeter, as in the present case, I prefer to inter-- 45.

pose a condenser l1 between the milliammeterand. the plate terminals to prevent the passage of direct current without-interfering with the pas-' sage of alternating current; The meter is provided' with a scale it which is marked in terms 50' of tube -qua'lity. Any suitable mark may. be used which will designate the several qualities it "is desired to indicate and, in the present instance, the" scale is divided intouthree; parts marked respectively, goodfi;fair. and. ipoorfj 551 and the pointer 19 moves over this scale when current is passed through the meter. 7

Selective means are provided for connecting the electrical center of the filament terminals of the socket in which the tube is to be tested with a source ofcurrent and, in the present arrange ment, a conductor 20 is connected with terminals 2! and 22 which are adapted to beconnected respectively with the source of grid current and the source of plate current. A resistance 23 is con nected at its center with a conductor 24 leading to the conductor 20. One endof this resistance is connected by a conductor 25 withthe filament terminals F of the several sockets. The other end of the resistance is connected by a conductor 26 with themovable contact member 2 of a selecting switch. This switch also comprises a series of stationary contacts, one for each socket, and these stationary contacts are connected, re-

spectively, by conductors 29 with the filament terminals F of the several sockets. In operating the device it is only necessary to move the movable switch member 27 into engagement with the stationary contact 28 for the socket in which the tube,

to be tested,'.the,several stationary contacts being marked by numbers, or otherwise, to indicate the type of tube which is to be tested in each socket. The tube is then placed in the socket and the plate, current passing through themeter, and 'a part, of the, resistance 16, will cause the pointer to be moved to a position to indicate the quality of the tube. If. the plate current is nor p mal the pointer will move'to the designation good.-. If the plate current, is "so far below .5 normal that the tube is of little or no value the pointer will :indicatethe designation poor, and

iithe plate current is below normal and is still sufificientrfor operation the pointer will ,indicate the designation .fairfi' Associated with each socket isan electrical indicating device, which is preferablyin the form of a lamp 353, and means are provided under'the control of the, selecting switch, 21-48 to close the circuit through the lamp associated with that socket which has been selected by the selecting As there shown, the severalv lamps are.

device. connected by a; conductor 3| with one end of; a separate secondary transformer winding 32', the otherend of which is connected by a conductor 3-3 with the movable member 34 of a second switch.

Theother side of each lampis connected by a conductor 35-with the respective stationary contacts -36 ,of the second switch. The movable switch member 34 is so connected with the mov- :able switch member 2'! that it will be causedto move in unison therewith, as by an insulated link 31,. The arrangement of'the stationary contacts issuch that when the movable switch members are actuated the switch member 34 will close the circuit throughthat lamp which. is associated with, the socket which has been selected by the switch member 21, thus causing a light to show at particular socket in which the tube is to be placed. While I haveshown and described one embodi ment of my invention I wish it to be understood that I do not desire to be limited to the detailsthereof as various modifications may occurzto a person skilled in the art. 1

Having now fully described my invention, what I claim as'new and. desire to secure by Letters Patent, is: a V 1. In a tube testing apparatus, a plurality of tube sockets adapted to receive tubes of different types, means for supplying current to, the plate,

grid and filament terminals of the several sockets, .an indicating device interposed in the plate circuits and having a scale marked in terms of tube quality, a resistance connected in shunt across the terminals of said indicating device, the "several sockets having their plate terminals connected at points in said resistance determined by the character of the tubes which'the respective sockets are adapted to receive, wherebyany tube inserted in its socket will cause the same indication on said indicating device that will be caused by another tube of difierent type but of the same quality inserted in its socket.

2. In a tube testing apparatus, a plurality of tube sockets adapted to'receive tubes of different types, means tor supplying current to the plate, grid and filament terminals of the several sockets, an indicating device connected with a source ter of the filament terminals oieach socket with a source of current.

3. In a tubetesting apparatus, a plurality of tubesockets adapted to receive tubesof difierent types, means'forsupplying current to the plate; grid and filament terminals of the several sockets, an indicating device interposed in the plate circuits and having a scale marked in terms of tube 'quality, a resistance connected in shunt across theterminals of said indicatingdevice the several sockets having their plate terminalsconnected at points in said resistance determined by the characterof the tubes which the respective sockets are adapted to receive, a resistance connected at its center with a source of current supply and connected at one end-with one filament terminal of eachsocket, and selective means ,for connecting the other end of the last mentioned resistance with the other filament terminal or each socket.

4.1a a tube testing apparatus, an' indicating device having a scale marked in terms descriptive of tube quality, a resistance connected in shunt across the terminals of said indicating device a plurality of tube sockets adapted to receive tubes of different types andhaving their plate terminals connected at points in saidresistance determinedby the character of the tubes which therespective sockets are adapted to receive, means for supplying current to the plate, grid'andfilament terminals of said sockets, and

means for connecting the electrical center ofthe filament terminals of each of said'tube sockets withthe source of current supply;

tube sockets adapted to receive tubes of different types, means for supplying current'to the plate, grid and filament terminals of the several sockets, an indicating device interposed' in the plate circuits and having [a scale marked in terms of tube quality, a resistance connected in shunt across the terminals of said indicating device i the severalsoc'kets having [their plate terminals connected at pointsin said resistance determined. by the character of'the'tubes which th'e'respective sockets are adapt'ed to receive, aswitchhaw ing stationary contactsiconnected respectively with one "terminal. of 7 each socket, and

. I 5. Ina tube testing 'apparatus,*a plurality of 6. In a tube testing apparatus, a plurality of.

tube sockets adaptedto receive tubes of difierent types, means for supplying current to the plate,

grid and filament terminals of the several sockets, an indicating device interposed in the plate circuits and having a scale marked'interms of tube quality, a resistance connected shunt across the'terminals of said indicating device the several sockets having their plate terminals connected at points in said resistance determined by the character of the tubes'which the respec tive sockets are adapted to receive, selective means for connecting the electrical center of the filament terminals of the respective sockets with a source of current, and means controlled by said selective means for indicating the selected socket.

'7. In a tube testing apparatus,a plurality of tube sockets adapted to receive tubes of different types, means for supplying current to the plate,

grid and filament terminals of the several sockets, an indicating device interposed in the plate circuits and having a scale marked in terms of tube quality, a resistance connected in shunt across the terminals of said indicating device the several sockets having their plate terminals connected at points in said resistance determined by thecharacter of the tubes which the respective sockets are adaptedto receive, a switch hav- Q grid and filament terminals of the several sock ing stationary contacts connected respectively with 'one filament terminal of each socket, and

having a contact member movable successively into engagement with said stationary contacts, a resistance connected at separated points with said movable switch member and with the other filament terminal of each socket, means for con necting the last mentioned resistance between the first mentioned points of connection with a source of current, an electrical indicating device associated with each socket, and means controlled by said switch for selectively energizing the last mentioned indicating devices.

8. In a tubetestingapparatus, a plurality of,

tube sockets adapted to receive tubes of different types, means for supplying current to the plate, grid and filament terminals of the several sockets, an indicating device interposed in the I plate circuits and having a scale markedin terms of tube quality, a resistance connected in'shunt across the terminals of said indicating device the several sockets having their plate terminals connected at points in said resistance determined by the character of the tubes which the respective sockets are adaptedto receive, a switch having static-nary contacts connected respectively with one filament terminal of each socket, and having a contact member movable successively into engagement with said stationary contacts, a resistance connected at separated points with said movable switch member and with the other filament terminal of each socket,means for connect ing the last mentioned resistance between the first mentioned points of connection with a source of current, lamps associated with the respective sockets and each having a circuit, a switch interposed in the lamp circuits and having sepaf rate contacts connected with the respective lamp ets, an indicating device, and aresistance connected in shunt acrossthe terminals of said indicating device, the several sockets having their plate circuits connected at points in said resistance determined by the character of the tubes which the respective sockets are adapted to receive. r r

PAUL F. JACKSON. 

